Rolled-up blind driving mechanism

ABSTRACT

A rolled-up blind driving mechanism includes a chain of beads adapted to rotate a chain wheel assembly to further drive a torsional spring on a spring holder to rotate an axle sleeve in rolling up/letting off the blind, the torsional spring having two end tips, a curved connecting arm, and two coils connected between the connecting arm and the end tips of the rolled-up blind, the connecting arm and the end tips being disposed at two sides of an inside protruding portion of the axle sleeve for enabling the axle sleeve to be rotated to roll up/let off the blind of the rolled-up blind when pulling the chain of beads to rotate the chain wheel assembly clockwise/counter-clockwise on the spring holder.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a rolled-up blind and, more specifically, to a rolled-up blind driving mechanism, which can easily be operated with less effort to roll up/let off the blind of the rolled-up blind.

[0002]FIG. 1 shows a conventional rolled-up blind 9. This structure of rolled-up blind 9 comprises a driving mechanism 90 adapted to roll up or let off the blind 97. The driving mechanism 90 comprises a chain wheel assembly 92, an axle sleeve 95 supported on the chain wheel assembly 92 and coupled to the blind roller 96 of the rolled-up blind 9, a spring holder 93, a torsional spring 94 mounted on the spring holder 93, and a chain of beads 91 hung on the chain wheel assembly 92 (see also FIG. 2).

[0003] When pulling the chain of beads 91 to rotate the chain wheel assembly 92, the torsional spring 94 is forced to rotate the axle sleeve 95 and the blind roller 96, causing the blind roller 96 to roll up or let off the blind 97. When released the chain of beads 91, the mechanical friction between the torsional spring 94 and the spring holder 93 stops the axle sleeve 95 from rotation. When rotating the axle sleeve, the torque applied to the torsional spring 94 must surpass the friction force between the torsional spring 94 and the axle sleeve 95 so that the torsional spring 94 can be released from the spring holder 93 and rotated relative to the spring holder 93.

[0004] However, because the torque can only be applied to one end tip 98 and then to the coil 99 of the torsional spring 94, much effort should be employed to the torsional spring 94 to release the coil 99 from the spring holder 93 due to long arm of force (torque=force×arm of force). It is known that reducing the number of turns of the coil 99 of the torsional spring 93 shortens the arm of force. However, a torsional spring having less number of turns is not suitable for use in a bid scale rolled-up blind.

SUMMARY OF THE INVENTION

[0005] The present invention has been accomplished under the circumstances in view.

[0006] It is the main object of the present invention to provide a driving mechanism for a rolled-up blind, which provides sufficient brake force to stop the blind roller from rotation and, can be operated to rotate the blind roller with less effort.

[0007] According to the present invention, the rolled-up blind driving mechanism comprises a chain of beads adapted to rotate a chain wheel assembly to further drive a torsional spring on a spring holder to rotate an axle sleeve in rolling up/letting off the blind. The torsional spring has two end tips, a curved connecting arm, and two coils connected between the connecting arm and the end tips of the rolled-up blind. The connecting arm and the end tips are disposed at two sides of an inside protruding portion of the axle sleeve for enabling the axle sleeve to be rotated the end tips/connecting arm of the torsional spring to roll up/let off the blind of the rolled-up blind when pulling the chain of beads to rotate the chain wheel assembly clockwise/counter-clockwise on the spring holder.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a sectional view showing a rolled-up blind driving mechanism installed in a rolled-up blind according to the prior art.

[0009]FIG. 2 is a sectional view taken along line A-A of FIG. 1.

[0010]FIG. 3 is an elevational view of a rolled-up blind driving mechanism constructed according to the present invention.

[0011]FIG. 4 is an exploded view of the rolled-up blind driving mechanism according to the present invention.

[0012]FIG. 5 is a longitudinal view in section of the rolled-up blind driving mechanism according to the present invention.

[0013]FIG. 6 is a sectional view taken along line C-C of FIG. 5.

[0014]FIG. 7 is a sectional view showing the rolled-up blind driving mechanism installed in a rolled-up blind according to the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] Referring to FIGS. from 3 through 5, a rolled-up blind driving mechanism 10 is shown comprised of a chain wheel assembly 1, a chain of beads 2, a wheel cap 3, an axle sleeve 4, a spring holder 5, a torsional spring 6, and a split pin 7.

[0016] The chain wheel assembly 1 comprises a chain wheel 11 on which the chain of beads 2 hung and pulled to rotate the chain wheel assembly 1 clockwise/counter-clockwise, a center through hole 13 extended through the center of the chain wheel 11 and adapted to receive the spring holder 5, a semispherical shell 12 axially extended from one side of the chain wheel 11 around the center through hole 13. The semispherical shell 12 has a first side edge 14 and a second side edge 15 adapted to drive the torsional spring 6 (this will be described further).

[0017] The wheel cap 3 comprises a cap ring 31 adapted to receive the semispherical shell 12 of the chain wheel assembly 1, and a smoothly arched cap flange 32 perpendicularly backwardly extended from the periphery of the cap ring 31 and adapted to hold the chain of beads 2 in engagement with the chain wheel 11 of the chain wheel assembly 1.

[0018] The axle sleeve 4 comprises a sleeve hole 41 axially extended through front and rear ends thereof, a retaining groove 42 axially extended in the periphery for engagement with the positioning rid 82 of the blind roller 81 (see FIG. 7) for enabling the blind roller 81 to be synchronously rotated with the axle sleeve 4, and an inside protruding portion 43 protruded from the inside wall thereof, The inside protruding portion 43 has a first sidewall 44 and a second sidewall 45 (see FIG. 6). When the semispherical shell 12 of the chain wheel assembly 1 inserted into the sleeve hole 41 of the axle sleeve 4, the first side edge 14 of the semispherical shell 12 faces the first sidewall 44 of the inside protruding portion 43, and the second side wedge 15 of the semispherical shell 12 faces the second sidewall 45 of the inside protruding portion 43 (the effect of this arrangement will be described further).

[0019] The spring holder 5 comprises an end cap 51, a shaft 52 axially extended from the center of one side of the end cap 51, and a pinhole 53 axially extended through the end cap 51 and the shaft 52. The pinhole 53 has a substantially D-shaped cross section. The shaft 52 is inserted into the center through hole 13 of the chain wheel assembly 1, keeping the end cap 51 engaged with one side of the chain wheel 11.

[0020] The torsional spring 6 is made of a resilient spring wire by winding, comprising two end tips 63, a curved connecting arm 62, and two coils 61 connected between the end tips 63 and two distal ends of the curved connecting arm 62 and sleeved onto the shaft 52 of the spring holder 5 in an interference-fit manner The friction force between the coils 61 and the shaft 52 prevents the blind from being automatically let off. The free end of the curved connecting arm 62 is inserted into the space between the second side edge 15 of the semispherical shell 12 of the chain wheel assembly 1 and the second sidewall 45 of the inside protruding portion 43 of the axle sleeve 4 (see FIG. 6). The end tips 63 of the torsional spring 6 are inserted into the space between the first side edge 14 of the semispherical shell 12 of the chain wheel assembly 1 and the first sidewall 44 of the inside protruding portion 43 of the axle sleeve 4 (see FIG. 6). When rotating the chain wheel assembly 1, the torsional spring 6 is driven to rotate the axle sleeve 4.

[0021] The split pin 7 comprises a first end 71 and a second end 72. The first end 71 is shaped like a truncated cone. The greatest diameter of the first end 71 is greater than the diameter of the body of the split pin 7, so that a shoulder 73 is defined between the first end 71 and the body of the split pin 7. A longitudinal split 74 extends axially through the first end 71. The second end 72 has a D-shaped cross section fitted into the pinhole 53 of the spring holder 5. A stop rod 75 is extended from the second end 72, having a bottom notch 76. After insertion of the split pin 7 through the pinhole 53 of the spring holder 5 and the sleeve hole 41 of the axle sleeve 4, the shoulder 73 is stopped at the front end of the axle sleeve 4, keeping the spring holder 5 secured to the axle sleeve 4. Because the second end 72 has a D-shaped cross section fitting the D-shaped cross section of the pinhole 53 of the spring holder 5, the spring holder 5 is prohibited from rotary motion relative to the split pin 7. When assembled, a gap 77 is left between the end cap 51 of the spring holder 5 and the top rod 75 for the positioning of the bracket, referenced by 84 to stop the split pin 7 from falling out of position (see FIG. 7). Further, other fastener means, for example, screw means may be used instead of the split pin 7 to secure the spring holder 5 to the axle sleeve 4.

[0022] Referring to FIGS. 6 and 7, when pulling the chain of beads 2 to rotate the chain wheel assembly 1 clockwise after installation of the rolled-up blind driving mechanism in the rolled-up blind 8, the second side edge 15 of the semispherical shell 12 of the chain wheel assembly 1 is forced against the connecting arm 62 to release (expand) the coils 61, thereby causing the torsional spring 6 to rotate on the shaft 52 of the spring holder 5, and at this time the end tips 63 of the torsional spring 6 are forced against the second sidewall 45 of the inside protruding portion 43 of the axle sleeve 4, causing the axle sleeve 4 to rotate the blind roller 81 in letting off the blind 83.

[0023] On the contrary, when pulling the chain of beads 2 to rotate the chain wheel assembly 1 counter-clockwise, the first side edge 14 of the semispherical shell 12 of the chain wheel assembly 1 is forced against the end tips 63 to release (expand) the coils 61, thereby causing the torsional spring 6 to rotate on the shaft 52 of the spring holder 5, and at this time the end tips 63 of the torsional spring 6 are forced against the first sidewall 44 of the inside protruding portion 43 of the axle sleeve 4, causing the axle sleeve 4 to rotate the blind roller 81 in rolling up the blind 83.

[0024] When released the chain of beads 2, the coils 61 immediately return to their former shape and are positively secured to the periphery of the shaft 52 of the spring holder 5 due to the effect of interference fit, keeping the blind 83 in position, and therefore the blind 83 is prohibited from extending out.

[0025] A prototype of rolled-up blind driving mechanism has been constructed with the features of FIGS. 3˜7. The rolled-up driving mechanism functions smoothly to provide all of the features discussed earlier.

[0026] Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

What the invention claimed is:
 1. A rolled-up blind driving mechanism comprising: a chain wheel assembly, said chain wheel assembly comprising a chain wheel, a center through hole extended through the center of said chain wheel, a semispherical shell axially extended from one side of said chain wheel around the center through hole of said chain wheel, said semispherical shell having a first side edge and a second side edge; a chain of beads hung on said chain wheel of said chain wheel assembly for pulling by hand to rotate said chain wheel assembly; a wheel cap, said wheel cap comprising a cap ring adapted to receive the semispherical shell of said chain wheel assembly, and a smoothly arched cap flange perpendicularly backwardly extended from the periphery of said cap ring and adapted to hold said chain of beads in engagement with said chain wheel of said chain wheel assembly; an axle sleeve, said axle sleeve comprising a sleeve hole axially extended through front and rear ends thereof and adapted to receive the semispherical shell of said chain wheel assembly, a retaining groove axially extended in the periphery thereof for engagement with the positioning rid of the blind roller of the rolled-up blind in which the rolled-up blind driving mechanism is installed, and an inside protruding portion protruded from an inside wall thereof, said inside protruding portion having a first sidewall and a second sidewall; a spring holder, said spring holder comprising an end cap engaged with one side of said chain wheel of said chain wheel assembly, and a shaft axially extended from the center of one side of said end cap and inserted into the center through hole of said chain wheel assembly; a torsional spring mounted on the shaft of said spring holder; and fastener means, which secures said spring holder to said axle sleeve; characterized in that said torsional spring comprises a curved connecting arm inserted into the space inside said axle sleeve between the second side edge of said semispherical shell of said chain wheel assembly and the second sidewall of said inside protruding portion of said axle sleeve, two coils mounted on the shaft of said spring holder inside said axle sleeve, said coils each having an inner end respectively connected to two distal ends of said curved connecting arm and an outer end, and two end tips respectively connected to the outer end of each of said coils and inserted into the space inside said axle sleeve between the first side edge of said semispherical shell of said chain wheel assembly and the first sidewall of said inside protruding portion of said axle sleeve.
 2. The rolled-up blind driving mechanism as claimed in claim 1 wherein said torsional spring is made of a spring wire by winding.
 3. The rolled-up blind driving mechanism as claimed in claim 1 wherein said spring holder comprises a pinhole of non-circular cross section axially extended through said end cap and said shaft; said fastener means is a split pin inserted through said pinhole of said spring holder to secure said spring holder to said axle sleeve, said split pin comprising a conical first end disposed outside said spring holder and said axle sleeve, a shoulder stopped at one end of said axle sleeve, a second end of non-circular cross section fitted into said pinhole of said spring holder, and a stop rod extended from said second end for positioning in the bracket of the rolled-up blind in which the rolled-up blind driving mechanism is installed. 